This grant application is designed to provide the candidate with intensive training in molecular biology to complement his background in clinical internal medicine and cardiology. This basic science training will allow him to-investigate the physiology and pathophysiology of cardiac systems at the molecular level. During Phase I -of this program, the candidate will join the laboratory of Dr. Leslie Leinwand, Director of the Sue Golding Graduate Division, Head of the Division of Molecular Cardiology, and Associate Professor in the Department of Microbiology and Immunology at the Albert Einstein College of Medicine. This laboratory has been active in using molecular genetics to elucidate contractile protein structure and function. A variety of approaches have been used, including bacterial expression of eukaryotic proteins, as well as functional domain mapping of such proteins, utilizing wild-type and mutant constructs In addition, the response of many components of the contractile apparatus during developmental stages and in response to pathologic states have been studied. The candidate hopes to draw upon the expertise available in this laboratory and apply these techniques to an understanding of the role of gap junctions in cardiac development, inter-cellular communication, and participation in and response to various pathologic states. Research activities will be complemented with selected courses in the Graduate Division at Albert Einstein College of Medicine, as well as strong interaction between the basic and clinical departments at Einstein. During Phase II of this program, the candidate will continue under the guidance of Dr. Leinwand as primary sponsor, and be joined by Dr. James Scheuer, Chairman of the Department of Medicine, Dr. Edmund Sonnenblick, Chief of the Division of Cardiology, and Dr. David Spray, Professor in the Department of Neurosciences, at the Albert Einstein College of Medicine, as well as Dr. Paul Cannon, Chief of the Division of Cardiology and Dr. J. Thomas Bigger, Jr., Director of the Arrhythmia Control Unit at Columbia University College of Physicians and Surgeons. This committee will provide guidance in designing appropriate research proposals during this second phase, ana supervise the candidates transition from a trainee into a more independent investigator.